There are many instances where particulate material are delivered through chutes or other discharge devices to various destinations, where dust is released from the particulate commodities causing an environmental hazard or a nuisance from pollution or contamination. Such instances may include the delivery of grains such as wheat or corn from silos or other holding vessels into the holds of ships or railway cars, or the transfer of other particulate commodities such as coal from one conveyor to another or to a required delivery point or stockpile.
It has been recognized that the dust typically entrained with such particulate commodities, also known as fines, are prone to be emitted from the product stream as dust during handling, which at the least can be a nuisance due to cleanliness requirements, or at the worst can form an environmental hazard. One recognized way of controlling dust in these situations is to reduce the velocity of the product stream to keep the relative velocity of the air stream over the product below the minimum pick up velocity of the dust, but such an approach has the disadvantage of limiting the rate at which particulate product can be delivered to the destination, and hence is a limitation on the efficiency of the process.